<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <style>
    html {
      font-size: 12px;
    }
    div {
      font-size: 12px;
      width: 15rem;
      height: 15rem;
      background-color: purple;
    }
    p {
      width: 10rem;
      height: 10rem;
      background-color: pink;
    }
  </style>
  <body>
    <div>
      <p></p>
    </div>
  </body>
</html>
